What are the signs of an approaching tsunami?

I added a bit to my last answer

There are many signs of an approaching tsunami to warn you. The first is that you should recognize the original cause of the tsunami. If there is an earthquake in the ocean then straight away you should know that there is a chance a tsunami is coming. It is easy to recognize an earthquake because you can feel the ground shake.

If there is a land volcanic eruption you will be able to see the smoke and feel the ground shake and then you should know that a tsunami is coming. An underwater volcanic eruption is harder to recognize because there is no smoke but you can still feel the ground shake.

If a meteorite lands in the ocean you may be able to recognize it because of it roaring through the sky and the smashing of it into the water.

A very clear sign that something is going to happen is the behaviour of animals. Animals can sense when a tsunami is coming long before humans can. In the Asian tsunami many people saw birds flying inland and making loud noises which was the signal that a tsunami was coming.

The main sign of an approaching tsunami is water rushing away from the shore. When a tsunami is approaching the waves suck all the water away from the shore to gain height and power. The water looks like it is retreating to the horizon. From the time the water is sucked away to the time it hits the shore is a few minutes.